Check If We Can Form Array from Pieces in Python

Suppose we have an array nums where all elements are unique and have another array with different smaller arrays called pieces. We have to check whether we can get the main array nums by concatenating the arrays in pieces in any order or not. But we are not allowed to reorder the elements present in each array pieces[i].

So, if the input is like nums = [5,1,12,36,2,47,6] pieces = [[2,47,6],[12,36],[1],[5]], then the output will be True because we can concatenate them in this order [[5], [1], [12,36], [2,47,6]] to get the main array.

To solve this, we will follow these steps −

• temp := a new list

• for each p in pieces, do

  • if p[0] not present in nums, then

    • return False

  • l := size of p

  • indx := index(p[0]) in nums

  • if subarray of nums from index indx to indx+l-1 is not same as p, then

    • return False

  • otherwise,

    • append p after temp

• if size of nums is same as size of temp, then

  • return True

• otherwise,

  • return False

Example (Python)

Let us see the following implementation to get better understanding −

 Live Demo

def solve(nums, pieces):
   temp = []
   for p in pieces:
      if p[0] not in nums:
         return False
      l = len(p)
      indx = nums.index(p[0])
      if nums[indx:indx+l] != p:
         return False
      else:
         temp.extend(p)
   if len(nums) == len(temp):
      return True
   else:
      return False

nums = [5,1,12,36,2,47,6]
pieces = [[2,47,6],[12,36],[1],[5]]
print(solve(nums, pieces))

Input

[5,1,12,36,2,47,6], [[2,47,6],[12,36],[1],[5]]

Output

True